The duo appeared to ignore each other as they got out of their cars, as they prepare for Thursday's international friendly with Costa Rica.
De Gea has been strongly linked with a move to Real Madrid, as per the Mirror, and that will put a question mark over Iker Casillas' future at Los Blancos.
The Manchester United goalkeeper has been named Player of the Year at his present club in consecutive seasons but, according to AS, the Red Devils are prepared to play hardball with the Spanish giants.
Casillas got out of his car and went to sign some autographs, but moved on as de Gea did the same.
Speculation regarding De Gea's impending arrival at the Bernabeu continues to gather pace, and that must be playing on Casillas' mind a little. If United's first choice keeper does move to Madrid, the latter may have to settle for a regular spot on the bench – a standing the 34-year-old is not too familiar with.
Although in 2013-14 Casillas was second choice to Diego Lopez, it was only a matter of time before he returned between the sticks and he will not want to surrender his position again.